The present invention relates to a process for the preparation of 2,3-dimercaptosuccinic acid and esters thereof. The 2,3-dimercaptosuccinic acids and esters thereof which can be prepared by the present process may be represented by the formula: ##STR1## wherein R is H or lower alkyl containing from 1 to 3 carbon atoms. When R is H, then the 2,3-dimercaptosuccinic acid is prepared and when R is lower alkyl, the corresponding esters are prepared.
The prior art teaches a two-step synthesis of 2,3-dimercaptosuccinic acid involving the addition of two moles of thiolacetic acid across the triple bond of acetylene dicarboxylic acid followed by an alkaline hydrolysis of the resulting 2,3-diacetyldimercaptosuccinic acid. This can be shown schematically as follows: ##STR2## Although this process results in the preparation of the desired compound, it requires the use of thiolacetic acid which is toxic and also expensive.
It is, therefore, an object of this invention to provide a novel process for the preparation of 2,3-dimercaptosuccinic acid and esters thereof.
It is a further object of this invention to provide a process for the preparation of 2,3-dimercaptosuccinic acid and esters thereof which does not require the use of thiolacetic acid.
Other objects and advantages of the present invention will be apparent from the following description.